Vaporizing liquid, especially the vaporization of water, is a very common technology. The traditional approach to vaporizing water involves heating a pool of water to its boiling temperature and capturing the vapor that evolves from the liquid. A common vaporization technology uses shell and tube-type boiler designs. In the case of smaller shell and tube-type boilers, the water to be vaporized resides in the spaces around heat exchange tubes. In the case of larger shell and tube-type boilers, the water flows internally through heat exchange tubes that are heated by heat external to the tubes.
The inability to generate steam quickly in response to demand is common to most conventional boiling technologies. For quick start applications, conventional boilers must be maintained in a hot stand-by mode. Other disadvantages of conventional boiler technologies can include the large thermal mass of liquid water that contributes to slow responses to transients, limited ability to thermally integrate the boiler with multiple heat streams or heat sources, and limited ability to utilize the boiler for heating materials other than the liquid to be vaporized.
In addition, another well known disadvantage associated with conventional boilers is the occurrence of liquid carry-over or slugging, wherein non-vaporized liquid is carried over with the vaporized liquid. Where the vaporized product required is a high quality steam, means must be employed to separate and remove the non-vaporized liquid from the steam. Means that are commonly employed to remove such carry-over from steam include knock-out or steam drums. However, for a system that utilizes a knock-out drum, the start-up time required to begin producing the vapor product is heavily dependent upon the size of the knock-out drum, and such times can range up to several hours. Further, means required to separate and remove liquid components from vaporized liquid will increase the size, cost and complexity of the vaporization apparatus.